Various dispersing devices are available. Most of them are based on vibration of some sort and are designed for automatic weighing systems, most commonly combination weighers. A combination weigher is designed to make groups of product, weights of which are to be as close as possible to a predetermined weight. Typically there is a target weight, which must be matched or exceeded with minimum over-weight. A combination weigher receives product in bulk from some infeed device and disperses the product to several pool hoppers, each of which is above a weighing hopper. The amount of product collected in each pool hopper is usually significantly less than the target weight, e.g. ¼-⅛ of the target weight. The product is released from the pool hoppers and into the weighing hoppers where it is weighed. The controller of the combination weigher will then calculate the optimum combination of the weighing hoppers such that their combined weight is exactly the target weight or as little above it as possible. The combination weigher then releases the product from these hoppers into an outlet trough or on an outlet conveyor. After each drop, the hoppers, which were emptied, are filled again from their respective pool hoppers and the pool hoppers are filled by activating the section of the dispersion device leading to that hopper. There are mainly two types of combination weighers; either the weighing hoppers are ranged circularly about a common axis or they are in linear arrangement. In the former type the dispersion device is located in the centre of the circular array of the weighing units. The product fed to its central portion is dispersed in the radial direction and supplied to the pool hoppers. In the latter type, the dispersion device is behind the weighing hoppers and the product is fed to the inlet-end of the dispersion device while the outlet is next to the weighing hoppers. In both cases the functionality is essentially the same. Combination weighers do not always have one pool hopper above each weighing hopper. The product in the pool hoppers can be weighed such that better control is achieved of the weight of each product group accumulated in the pool hopper before it is released to the weighing hopper. There can also be multiple pool hoppers above each of the weighing hopper to ensure quicker filling of the weighing hoppers. That is especially useful if the dispersion device does not reliably feed product when activated. Yet another variation is to have a pool hopper underneath the weighing hopper such that the product in the weighing hopper can either be released to the outlet trough or into the pool hopper. This gives the controller more possible combinations as the weight of the product in the pool hoppers underneath the weighing hoppers is known. More possible combinations will on average lead to better performance of the combination weigher, that is lower over-weight or more capacity.
Combination weighers are well known but being able to use them reliably on fresh, sticky and delicate food products has been the problem up to know.
Several patents exists for dispersion devices. One of the first patents for an automatic weighing device with a dispersion device as a critical component is U.S. Pat. No. 4,398,612. Another, newer patent, which also describes a dispersion device to disperse product to a circular array of weighing hoppers is U.S. Pat. No. 4,561,510. Similar device has also been patented in U.S. Pat. No. 4,600,096. These patents have in common that there are multiple dispersion devices which operate on the same pile of products and they can be individually controlled and thus used to selectively feed multiple weighing hoppers or pool hoppers above weighing hoppers. Most of these devices are designed for firm non-sticky product but some attempts have been made to make dispersion devices for sticky products that can not be conveyed by vibration. One example is U.S. Pat. No. 4,662,508 where rotating discs in an horizontal plane are used to disperse the product Another example is U.S. Pat. No. 6,493,605 where e.g. flexible tabs and vertical movement of the inlet chute are used to obtain more uniform feeding on the dispersion tables. These feeding devices have that in common that they are not gentle enough on delicate food products and can therefore not be used for the problem at hand.
Another feeding device along with a weighing unit has been patented in U.S. Pat. No. 4,122,941. Although this device is mechanically somewhat similar to the dispersion unit of the present invention it is neither an in-feed control nor a dispersion device. This unit is designed to be manually fed and the feeding mechanism is designed to selectively shift individual product items from one slot to the next. It is also not ensured that the stationary carrier bars are sufficiently thick that the top part of the moveable bars will never go beneath the lower part of the stationary carrier bars. This means that the tail of a fresh fish fillet which can easily slide between the carrier bars could get cut or damaged.
A feeding device similar to the one described here above is designed to feed fruit products to a fruit grading machine has been patented in U.S. Pat. No. 5,613,595. Again this is not an in-feed control apparatus as the amount of product being fed can not be accurately controlled. Furthermore is it not ensured that the stationary carrier members are sufficiently thick that the top part of the moveable carrier member will never go beneath the lower part of the stationary carrier member. Delicate food product which can slide between the stationary carrier member can therefore get cut or damaged.
In the light of the foregoing it is clear that there still remains a need for more suitable automatic apparatus to feed and handle fresh, sticky and delicate food products, especially where accurate control of the throughput is needed.